With the looming CAFE fuel economy standards, just about every automaker out there is pushing hard to migrate from larger displacement engines to engines with a smaller displacement, typically using a turbocharger to get the same sort of power output. The benefit of this is that it allows drivers to have the same performance with improved fuel economy.

One of the most successful automakers at making this transition away from higher displacement engines has been Ford with its line of EcoBoost power plants. Detroit News reports that Ford is projecting an increase in sales for vehicles using four-cylinder engines and that by 2020 66% of all new vehicles will use smaller displacement four-cylinder engines.

"I think it's maybe a stretch. But I don't find it implausible," said Bill Visnic, senior editor at the car research site Edmunds.com, in a telephone interview. "If you look at where things have been going segment by segment, except pickups, you could say that's been the trend."

In 2008, only 40% of new vehicles sold used four-cylinder engines compared to 53% today. Currently, the majority of small and medium-size cars on the automotive market come standard with a four-cylinder engine. Most compact SUVs also come standard with four-cylinder engine. Full-size pickups and full-size SUVs currently come with six and eight-cylinder engine options. In 2012, sales of pickup trucks accounted for 13% of all new market sales.

Mike Osmotoso of LMC Automotive notes that to achieve that 66% goal, "[Ford would be] expecting pickups and full-size SUVs to virtually disappear."

quote: Strength of materials starts to mean less as you have momentum and inertia to deal with.

There are 12k lb trucks towing 30k lbs of weight. How does that work then? A 3000 lb truck CAN tow more weight IF the structure is strong enough. The reason why trucks weigh so much is because of the weight of the of the structure needed to tow/haul X amount of weight. Lighten AND strengthen the structure and you can keep towing/hauling the same weight. That said, in reality, you still aren't going to get a 3000 lb truck that tows/hauls too much more than what it already does now IMO and the cost of lightening the truck may not be worth the additional expense and fuel savings. IMO trucks worst enemy is not weight but aerodynamics.

It's not the strength of the truck frame that becomes a problem, or the ability to pull the weight.

It's the pure dynamics of having a significantly heavier weight following a lighter one. It becomes an unstable system. The heavier towed load can literally push the truck around in braking scenarios (aka, jackknife) or cause unstable turns.

As for my numbers, I admit I just pulled them out of the blue, but my point still stands. It's not a linear relationship, but getting a truck too light would definitely affect its towing ability. Now I'm sure that would be accounted for when manufacturers rate the capacity.

True, that effect can be mitigated by load distribution, better suspension, structural stiffness and wheels. Reducing weight saves fuel, costs, wear on roads, etc... The reduction in haul and tow capabilities will probably not affect most truck buyers.

The heavy duty trucks will always stay heavy for their intended purpose. Most F150 buyers won't haul or tow that much stuff or ever. There are those who do use a truck because they need its capabilities and those trucks are still available.

Not really concerned with your exact numbers as I got wheat you were saying but trucks that are half the weight of their loads (and more) are driven daily AND are within manufacturers guidelines and state and local regulations. It's a non-issue. Only a portion of the towed weight is carried by the tow vehicle anyways. Only under braking does the tow vehicle possibly experience heavier loading. And that heavier load under braking is compensated for by the use of trailer brakes. It's mandatory over a certain towed weight to have them (and the weights are really low like 1500 lbs in CA). There is NO truck in ANY weight class that's rated to stop its combined gross weight without braking assistance from the trailer. I stand by my post that says that a lighter truck with the proper strengthening can tow the same amount of weight as the heavier truck. I also stand by my opinion that trucks won't get significantly lighter in reality due to cost and other issues.

My only point was that it will always be safer to tow with a heavier vehicle than a lighter one. Can it be done? Yes. Should it for the average person? No.

Trailer brakes still only help in strait line deceleration. In an emergency situation, the momentum of the trailer could cause the system to become unstable.

We don't really have to guess on this. A Ford Ranger can't tow the same capacity as the F150. Yes, there's plenty of factors involved, but if suddenly Ford was miraculously shave 1/4 the weight off the F150, then I guarantee you'd see a reduction in ultimate tow capacity.

And I do completely agree that I don't think we'd ever see a significant reduction in weight anytime soon.

Anyone with a clue of how obvious that statement was wouldn't have put in the stupid disclaimer.

It has instantly made me think more "assembly line dogsbody" and less "knowledgeable engineer".

In answer to your question, different operating regimes will have different dependencies, higher speeds lead to more bias towards aerodynamics, lower speeds towards weight. There is no single number that catches all. If your doing a lot of intersate, aerodynamics. If your shuttling around a farm and going no distance pretty slowly - weight.

Another significant factor omitted is drivetrain friction and inertia.

If you're doing a lot of ultra urban, inner city driving (like say...in downtown Manhattan or in downtown Chicago) - probably moreso mass. Cuz you keep having to accelerate and decelerate that mass. So a LOT of energy is spent just on MOVING the damn thing.

But if you're doing say...a constant 75 mph - mehhh...that depends.

If you design the pick-up so that it "LOOKS" like a pick-up today (big, huge, bulky, like a brick), then hurling a brick at 75 mph is going to encounter a lot of air resistance no matter how much you try to make a brick aerodynamic. But on the other than though, mass is somewhat more "predictable" in terms of fuel economy specifically because kinetic energy is 0.5*m*v^2.

So if you say..make a truck 10% lighter, the relationship between the two is pretty well linear. Aero - on the other hand is a LOT less "predictable". (I used to run the computational fluid stuff while I was an undergrad research - not for cars or an OEM, but the nature of fluids and computational fluids is as much an art as it is a science right now. And there's still a LOT of debate amongst CFD users about what is the best way that is the most generally applicable. And it doesn't help that 35 years later (roughly) - there STILL isn't a general concensus amongst the experts in the field give you a glimpse as to how difficult the problem is and how difficult making such a claim/statement is.

And part of it also comes as a result of the customers too. OEMs can probably MAKE a very aerodynamic pick-up truck, but by then, it probably wouldn't look anything like the pick-up truck that people know and have envisioned in their minds. So, they end up having to like "undo" that, and well...yeah...you end up with what you've got today amongst all of the pick-up truck manufacturers.

It's the same or very similiar idea with the CVT transmissions and how people were complaining that you couldn't feel it shift, so OEMs HAD to change the transmission control algorithm and put the "shift feel" back into the CVT (which basically made the whole point of a CVT moot or near-moot).

OEMs (in general) get a fair bit of that. People generally don't like change. But once in a while, people eventually realize that the change was for the better. Much, MUCH better.

(The basic drag force equation is 0.5*rho*v^2*Cd*A and if people want the frontal profile of a pick-up to be a brick, then pretty much almost all of those numbers are locked/fixed values either because they're constant for comparison purposes, or constrained, however artifically).

(Note: I cannot stress my disclaimer enough. Even though I work for an OEM, I've also worked in the supplier base as well as an automotive engineering analyst, so I am speaking for myself based on my discussions at conferences with experts and my collective experiences. And a little bit from having actually done bits and pieces of it as part of my studies/personal research.)

DISCLAIMER: The views and opinions expressed here are solely that of my own and are not representative of Ford Motor Company or its affiliates.